It is known that heat-resistant kitchen appliances for the household and industrial sector are manufactured to an increasing degree from glass-ceramic materials. In use, glass-ceramic cooking utensils in particular increasingly suffer from difficult-to-remove residues as a result of burning or even carbonization of foodstuffs spitting or boiling over. Without appropriate conditioning, the surface may be severely damaged by excessively vigorous scouring, and use of cleaning utensils such as glass scrapers can take chips out of the glass-ceramic surface, with consequent deterioration of the surface. In the case of foodstuffs with a high sugar content in particular, removal of the burnt-on food is virtually impossible without extensive damage to the surface.
The use of organopolysiloxanes in cleaning compositions, for example, solvents for window washing, car polishes, metal and textile cleaners, is well known. British Patent 1,172,479; British Patent 1,171,479; U.S. Pat. Nos. 3,681,122; and 4,124,523 all describe cleaners which consist of an organopolysiloxane, an alkali metal salt of the 3rd to 5th main group, a scouring agent and water as well as, if appropriate, a thickener and a non-ionic surfactant. It is true that these formulations are in principle suitable for the cleaning of glass-ceramic surfaces, but their conditioning action in protecting the surface is wholly inadequate. In particular, the protective effect against burnt-on residues of foods with a high sugar content is insufficient. German Offenlegungsschrift 3,321,289 discloses a water-in-oil emulsion which consists of an amine functional organopolysiloxane, a cyclic dimethylpolysiloxane, a polysiloxane polyoxyalkylene block copolymer, a scouring powder, a surfactant and water. It is true that the cleansing action of this formulation is equally effective, yet again the protective effect of the amine functional organopolysiloxane contained therein as protective-film former is unsatisfactory, especially where the burnt-on food residues have a high sugar content. German Patent 2,952,756 discloses compositions which contain a polysiloxane containing metal oxides and/or amine groups, a scouring agent or a cleaner and additional surfactants. Even though the compositions in question have a cleansing and conditioning action, they have a short shelf-life due to a continuous increase in viscosity, poor polishability, and inadequate protection against burnt-on foods having a high sugar content. German Offenlegungsschrift 3,327,926 discloses an emulsion formulation which is composed of an amine functional polydimethylsiloxane, emulsifiers, acid components, a solvent, a scouring agent, protective-film improvers and water. It is true that the preparations in question have a cleansing and conditioning action, yet they suffer from the same disadvantages as those described in German Patent 2,952,756.
Therefore, it is an object of the present invention to provide a cleaning and conditioning composition which removes residues from glass-ceramic surfaces. Another object of the present invention is to provide a composition which acts as a conditioning agent for the cleaned glass-ceramic surfaces and to prevent or reduce the formation of difficult-to-remove residues. Still another object of the present invention is to prevent deterioration of the glass-ceramic surface. Still another object of the present invention is to provide a protective film on the glass-ceramic surface to reduce the adhesion of burnt-on food and allows the surface to be cleaned easily and gently at any time. A further object of the present invention is to provide a composition which can easily be applied and polished and has no tendency to produce smears and streaks. A still further object of the present invention is to provide an improved cleaner and/or conditioner for glass-ceramics which does not have the disadvantages of the prior cleaners and/or conditioners.